To clarify things a bit...
Typically an "observership" is a position designed for foreign medical grads without any US clinical experience. Because they have already finished medical school, they are not eligible for the elective clerkships mentioned in the post above. Furthermore, many are unable to get paid positions in which they have clinical contact with patients due to liability issues. Therefore, the observership is rather popular with FMGs.
These are generally not formalized contracts, but set up on a case by case basis, usually directly with a faculty member or department. While the experience may yield the oh-so valuable LOR for these individuals, the drawback is that again, due to liability issues, most are not allowed to do anything more than observe - ie, they cannot do procedures, see patients alone, etc.
At any rate, to answer the OPs query, I don't have any information on such, but I'm sure if others do, we would appreciate it being posted here. That said, I'll move this to the International Forum where it is better suited.